Close Encounters

Biting People
There’s probably no aspect of shark behavior that interests people more than the very rare occasions when sharks bite humans. And when bites occur, they result in widespread attention, especially if injuries are serious or even fatal.

It’s important to keep these incidents in perspective, and to remember that in Hawai‘i the chances of being bitten by a shark are less than one in a million. The chances of being seriously injured by a shark are much less than that. But considering the tendency of some media to sensationalize sharks, and the fact that shark bites are such unusual events, it’s probably not surprising that when they occur they often generate attention out of proportion to the risk itself.

Shark Bites vs. Shark Attacks
When a dog bites a person, it’s usually called a dog “bite.” When a shark bites a person, it’s usually called a shark “attack.” If a dog bites someone repeatedly or viciously, it’s referred to as an attack. The same logic should be applied to sharks.

In most cases, sharks do not bite people repeatedly or viciously, but because sharks, especially big sharks, have powerful jaw muscles and very sharp teeth, any bite can cause considerable damage to human tissues. Still, it is more accurate to refer to such incidents as “shark bites,” rather than “shark attacks.” There are obvious cases where the term “shark attack” might be appropriate; but such cases are extremely rare.

Obviously, there are huge differences between dog and shark behaviors, especially when it comes to their interactions with people. So comparisons between the two must be made with caution. But along those lines, medical and public safety personnel often compare the injuries resulting from bites by smaller sharks with those of dog bites.

Tiger Sharks vs. Other Sharks
In Hawai‘i, tiger sharks are often identified as being responsible for incidents resulting in serious or fatal injuries. Identification can be based on victim or witness descriptions of the shark, or on physical evidence, such as tooth fragments or bite marks.

Throughout the world, tiger sharks are considered one of the three most dangerous shark species. As far as the other two are concerned, white sharks are rare in Hawaiian waters, and bull sharks do not occur in Hawai‘i at all.

Tiger sharks are considered particularly dangerous because of their size, and their indiscriminate feeding behavior. They will eat almost anything, and often feed on objects at the water’s surface. Although it’s never been proven, some bites on people may be the result of investigatory behavior; the shark bites an object (in this case a person) to determine whether it is an acceptable food source.

Although tiger sharks may be the most dangerous of Hawaiian sharks, other species have been known to bite people, usually with much less serious results. But as mentioned above, sharks have very sharp teeth, and even small sharks can cause significant tissue damage to a person.

Why Bite People?
Why sharks sometimes bite people is a question that is often asked, but so far has no single answer. Attempts to understand the “why” of shark bites are complicated by some significant challenges, which include the following.

We don’t have a very good understanding of shark behavior in general, and trying to extend what little we know of normal behavior to rare and unusual behaviors, like bites on humans, is difficult.

There is considerable variation in the behavior of sharks, not only of different species, but also among individuals within a species. As a result, attempts to generalize shark behavior have serious limitations. People who spend a lot of time studying sharks in the wild, including tiger sharks, often comment on their behavioral differences. Certain sharks seem to be very cautious and wary when approaching potential prey items, whereas others of the same species are much more aggressive.

We usually have no idea what a shark was doing in the moments just prior to biting someone. Therefore, it’s impossible in most cases to even speculate on what led up to the incident.

In spite of these challenges, scientists have been studying shark incidents for decades trying to better understand what attracts sharks, what may repel them, and what conditions and human behaviors may increase the risk of shark bites.

These studies continue, particularly in association with the International Shark Attack File (ISAF) at the University of Florida. Cooperating agents in Hawai‘i gather data about the details of shark incidents and submit them to the ISAF, where the information is added to a worldwide data base. Analysis of the large pool of data may provide insight into ways people can further reduce the risk of being bitten by a shark.